 | |
| Discovery[1] | |
|---|---|
| Discovered by | M. W. Buie (DES) |
| Discovery site | Cerro Tololo Obs. |
| Discovery date | 21 August 2001 |
| Designations | |
| (612243) 2001 QR322 | |
| 2001 QR322 | |
| Neptune trojan · L4[2] TNO[3] · distant[1] | |
| Orbital characteristics[3] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 3 | |
| Observation arc | 12.26 yr (4,479 days) |
| Aphelion | 30.968AU |
| Perihelion | 29.262 AU |
| 30.115 AU | |
| Eccentricity | 0.0283 |
| 165.27yr (60,363 days) | |
| 86.551° | |
| 0° 0m 21.6s / day | |
| Inclination | 1.3250° |
| 151.75° | |
| 151.11° | |
| Physical characteristics | |
| 132 km[4] | |
| 0.058[4] | |
| 22.5[5] | |
| 8.12[3][2] | |
(612243) 2001 QR322,prov. designation:2001 QR322, is aminor planet and the firstNeptune trojan discovered, by American astronomerMarc Buie of theDeep Ecliptic Survey atCerro Tololo Observatory in Chile on 21 August 2001.[1][6] It orbits ahead ofNeptune at itsL4Lagrangian point and measures approximately 132 kilometers (82 miles) in diameter.[2][4]
Other Neptune trojans have been discovered since. A study by American astronomersScott Sheppard andChad Trujillo from the Carnegie Institution suggests that Neptune could possibly have twenty times more trojans thanJupiter.[7]
2001 QR322 orbits the Sun with a semi-major axis of 30.115 AU at a distance of 29.3–31.0 AU once every 165 years and 3 months (60,363 days). Its orbit has aneccentricity of 0.03 and aninclination of 1° with respect to theecliptic.[3]
Early studies of the dynamical stability of2001 QR322, which used a small number of test particles spread over the uncertainties of just a few orbital parameters that were derived from a limited observation arc, suggested that2001 QR322 is on a remarkably stable orbit, because most test particles remained on trojan orbits for 5 Gyr. Thereafter, the stability of Neptune trojans was simply assumed.[8]
A more recent study, which used a very large number of test particles spread over the 3σ uncertainties in all six orbital parameters derived from a longer observational arc, has indicated that2001 QR322 is far less dynamically stable than previously thought. The test particles were lost exponentially with ahalf life of 553 Myr. Further observations can determine whether2001 QR322's orbit is actually within the dynamically stable or within the unstable part.[8]
The stability is strongly dependent onsemi-major axis, with a≥30.30 AU being far less stable, but only very weakly dependent on the other orbital parameters. This is because those with larger semi-major axes have largerlibration amplitudes, with amplitudes ~70° and above being destabilized by secondary resonances between the trojan motion and the dynamics of at leastSaturn,Uranus, and Neptune.Secular resonances were found not to contribute to the dynamical stability of2001 QR322.[8]
Thisminor planet wasnumbered and itsdiscoverer determined by theMinor Planet Center on 28 March 2022 (M.P.C. 139893).[1][9] If named, it will follow the naming scheme already established with385571 Otrera, which is to name these objects after figures related to theAmazons, an all-female warrior tribe that fought in theTrojan War on the side of the Trojans against the Greek.[10]
The discoverers estimate that the body has amean diameter of 132 kilometers with a lowalbedo of 0.058 at anabsolute magnitude of 8.12.[4] It has a visualmagnitude of 22.5.[5]
